Organic chemistry with biological applications

John E. McMurry

ISBN #9781285842912

3rd Edition

1,528 Questions

13,325 Students Helped

Homework Questions

Summary

Learning Objectives

Key Concepts

Example Problems

Explanations

Common Mistakes

Summary

This section covers the fundamental concepts of metabolism, elaborating on how catabolic pathways break down large biomolecules into smaller units to release energy, and how anabolic pathways build complex molecules requiring energy. Key processes include the hydrolysis of food during digestion, the transformation of macromolecules into acetyl CoA, and its subsequent oxidation in the citric acid cycle to produce ATP via the electron transport chain. Amino acid metabolism is featured heavily, showcasing the roles of transamination (facilitated by PLP), oxidative deamination, and the urea cycle in managing nitrogen waste. Moreover, understanding whether amino acid carbon chains are glucogenic or ketogenic provides insight into how they integrate into broader metabolic networks.

Learning Objectives

Key Concepts

CONCEPT

DEFINITION

Definition: The study of molecular reactivity via polar covalent bonds where differences in electronegativity create dipole moments, guiding acid–base behavior.

The study of molecular reactivity via polar covalent bonds where differences in electronegativity create dipole moments, guiding acid–base behavior. •

Example Problems

Example 1

One of the early steps in the urea cycle by which ammonia is excreted from the body is the reaction of bicarbonate ion $\left(\mathrm{HCO}_{3}^{-}\right)$ with ATP to yield carboxy phosphate. Write the reaction, and draw the structure of carboxy phosphate. You can check your answer in Figure 20.4

Example 2

Write all the steps in the mechanism of the transamination reaction of PMP with $\alpha$ -ketoglutarate plus a lysine residue in the enzyme to give the PLP-enzyme imine plus glutamate. The process is the reverse of that shown in Figure 20.2 .

Example 3

In the oxidative deamination of glutamate, is the hydride ion transferred to the Re face or the Si face of NAD $^{+}$ ? (Review Section 5-11.)

Example 4

Draw the full structure of the adenosyl monophosphate intermediate formed by reaction of citrulline with ATP (Figure 20.6 ).

Example 5

Review Section $20-2,$ and write all the steps in the PLP-dependent transamination reaction of alanine plus $\alpha$ -ketoglutarate to give pyruvate plus glutamate.